DMX is easy - all you need is a UART - I'm sure there are multiple Arduino libraries out there.
Yes there are quite a few libraries. However, I have realized that the software I am planning on using (and the number of pixels I need) will be better suited by using ArtNET or aSCN. ArtNET to dmx nodes are still pretty pricy, so I wonder if it might be better to build something using off the shelf mappable pixel ICs.
Actually, using this as a main controller looks promising too with its aSCN Input, 4 aSCN to dmx outputs, then I could build another finer resolution LED wall with its insane number of pixel outputs.
Then I could build a DMX interface with the arduino on each LED matrix. This seems to be the most affordable and expandable option!
http://www.advateklights.com/shop/mantis-pixel-mapping/16-pixlite-16-controller.htmlYou'd need multiple PWM outputs to control the drivers (assuming you want intensity control) - something like a PCA9685, which gives 16 channels from I2C. If you just need on/off control it's even simpler.
Yes, definitly need intensity.
Thanks, I have been reading the datasheet for the PCA9685. Looks really nice and pretty easy to use!
If low cost is the priority and you don't care about efficiency, you could get away with resistive current limiting and carefully controlled supply voltage, and a bunch of fan-cooled power resistors.
Cost doesnt have to be that low thankfully! I found a driver IC that looks pretty decent and affordable. A whole reel of 500 is under 30$ on alibaba
Ordered 10, we will see how they work.
http://www.electroschematics.com/wp-content/uploads/2014/07/PT4115E-datasheet.pdfSince I am using RGB LED's, I am thinking of build a board with 24 LED drivers each, and having 1 per row.
What colour? If white will do , look at using off-the-shelf LED filament lamp replacements, e.g. MR16 types with internal drivers.
I am looking at using RGB Led's like these
http://www.ebay.com/itm/RGB-LED-Light-Bulb-Beads-10W-Lamp-Bulb-1pc-High-Power-Super-Bright-Integrated-/400423640521?hash=item5d3b1bddc9:g:qFkAAOSw5dNWlKT~Unless you have a better suggestion. I ordered a few samples and have found they are not particularly consistent....would like to find a reputable supplier!
If your focus is only the LED Matrices, and you want to control them using for example Lightjams, I suggest you buy a USB to DMX module such as ENTTEC https://www.enttec.com/?main_menu=Products&pn=70303 or use the Arduino shield http://playground.arduino.cc/DMX/DMXShield although I don't think it will work on LJ.
On the other side, take into account how much current scales up when driving LEDs, it is easy to get beyond 5A when dealing with long runs of LED strips or muxed matrices. So design with that in mind.
Thanks. I have used the entec interface before. Pretty nice, but I need more channels
Yes, current consumption will be pretty high. Thankfully these run at 12v
On the other side, take into account how much current scales up when driving LEDs, it is easy to get beyond 5A when dealing with long runs of LED strips or muxed matrices. So design with that in mind.
If he is planning on using 5-10 watt RGB leds similar to THESE, he has bigger issues than just long runs:
400mA / color * 3 * 16 * 8 = 153.6 Amps @ ~ 3V = ~460Watts for White at full brightness. That's going to generate quite a bit of heat. More for the 10w LEDs
Maybe using WS2081's and then building an LED driver on top of them would be the easiest?
Yep, possibly. You will need a micro to process the DMX UART and output the SPI required for the WS2081's.
Yes, heat is one of the large unknowns as of now. They will be in a hot stage environment. I am thinking of building the frame that each LED mounts on out of 2" aluminum bar and mounting them directly to that. Trying to find a good passive way of dealing with the problem. I am also planning on running them with a relatively low duty cycle, but I want to stay conservative to make sure they last long!
If I was going to go the ws2081 route, seem like using an off the shelf artnet to pixel controller would be the simplest.